Together with the increase in the intensity of railroad traffic, the increase in the speed of the rolling stock and with the introduction of longer trains, the problem of reinforcing the base under the rails becomes acute. At present, concrete sleepers, which are more durable and have a longer life than traditional wooden sleepers, are widely used throughout the world. However, it is known that concrete sleepers have a greater stiffness which causes an increase in the stresses in the upper track structures and results in disturbances thereof. Stiffness of the track, as measurements show, is three and more times greater in the case of concrete sleepers than in the case of wooden sleepers, and this in turn has a negative effect on the stability of the track and on the operation of elements interacting therewith. A substantial disadvantage of concrete sleepers is their low resistance to corrosion in segments of track exposed to aggressive media, which substantially reduces their service life. Operating and manufacturing defects are also substantial.
At present sleepers are known which are made from reinforced polymer concrete, including therein at least one polymer capable of hardening, an appropriate hardener and filler with dispersed reinforcement with fibres. In particular, the use of furan polymer concrete, produced on the base of furfural acetone monomers, in rail beds is known. The durability of polymer concrete on the base of furfural acetone resins is determined primarily by the chemical activity of the binder and fillers such as gravel, sand, andesite flour. The hardener and different modifying components have some effect on the durability. The greater resistance of polymer concrete with dispersed reinforcement when a load is applied a multiple number of times makes this material especially appealing for the manufacture of sleepers. It should be noted that the possibility of using another type of polymer concrete is not excluded.
A sleeper is known which is disclosed in SU, A, 1276717, SU, A, 1276719, and has a body with a cross section which varies along the length of the sleeper, the body being made of reinforced polymer concrete with dispersed reinforcement in the form of steel and synthetic fibres, and with at least two inserts, the modulus of elasticity of the material of which is less than the modulus of elasticity of the body of the sleeper, at the points where it is presupposed the rails will be secured.
In spite of the achieved reduction of stiffness as compared with concrete sleepers, which substantially improves the property of resistance of the structure to the action of rolling stock, a disadvantage of the known sleeper is its greater stiffness as compared with a wooden sleeper, which results in substantial dynamic loads on the track and the rolling stock, and also substantial specific consumption of expensive materials--components of polymer materials (furfural acetone monomer, benzenesulphonic acid--hardener).